CVE-2021-28703

Published on: 12/07/2021 12:00:00 AM UTC

Last Modified on: 12/09/2021 04:17:00 PM UTC

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Certain versions of Xen from Xen contain the following vulnerability:

grant table v2 status pages may remain accessible after de-allocation (take two) Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated when a guest switched (back) from v2 to v1. The freeing of such pages requires that the hypervisor know where in the guest these pages were mapped. The hypervisor tracks only one use within guest space, but racing requests from the guest to insert mappings of these pages may result in any of them to become mapped in multiple locations. Upon switching back from v2 to v1, the guest would then retain access to a page that was freed and perhaps re-used for other purposes. This bug was fortuitously fixed by code cleanup in Xen 4.14, and backported to security-supported Xen branches as a prerequisite of the fix for XSA-378.

  • CVE-2021-28703 has been assigned by URL Logo [email protected] to track the vulnerability - currently rated as HIGH severity.
  • Affected Vendor/Software: URL Logo Xen Project - Xen version ! 4.13.4
  • Affected Vendor/Software: URL Logo Xen Project - Xen version ! 4.14.x
  • Affected Vendor/Software: URL Logo Xen Project - Xen version ! 4.15.x
  • Affected Vendor/Software: URL Logo Xen Project - Xen version <= 4.13

CVSS3 Score: 7 - HIGH

Attack
Vector
Attack
Complexity
Privileges
Required
User
Interaction
LOCAL HIGH LOW NONE
Scope Confidentiality
Impact
Integrity
Impact
Availability
Impact
UNCHANGED HIGH HIGH HIGH

CVSS2 Score: 6.9 - MEDIUM

Access
Vector
Access
Complexity
Authentication
LOCAL MEDIUM NONE
Confidentiality
Impact
Integrity
Impact
Availability
Impact
COMPLETE COMPLETE COMPLETE

CVE References

Description Tags Link
xenbits.xenproject.org
text/plain
URL Logo MISC xenbits.xenproject.org/xsa/advisory-387.txt

Known Affected Configurations (CPE V2.3)

Type Vendor Product Version Update Edition Language
Operating
System
XenXenAllAllAllAll
  • cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:*:

Social Mentions

Source Title Posted (UTC)
Twitter Icon @oss_security Xen Security Advisory 387 v2 (CVE-2021-28703) - grant table v2 status pages may remain accessible after de-allocati… twitter.com/i/web/status/1… 2021-11-24 02:30:13
Twitter Icon @usijoe IT Risk: SUSE.xenに複数の脆弱性 -2/2 CVE-2021-28703 CVE-2021-28701 CVE-2021-28698 CVE-2021-28697 CVE-2021-28692 CVE-2021-2… twitter.com/i/web/status/1… 2021-12-02 05:58:13
Twitter Icon @management_sun IT Risk: SUSE.xenに複数の脆弱性 -2/2 CVE-2021-28703 CVE-2021-28701 CVE-2021-28698 CVE-2021-28697 CVE-2021-28692 CVE-2021-2… twitter.com/i/web/status/1… 2021-12-02 06:42:33
Twitter Icon @CVEreport CVE-2021-28703 : grant table v2 status pages may remain accessible after de-allocation take two Guest get permit… twitter.com/i/web/status/1… 2021-12-07 11:18:18
Reddit Logo Icon /r/netcve CVE-2021-28703 2021-12-07 12:38:29
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